Solar microscope

a microscope consisting essentially, first, of a mirror for reflecting a beam of sunlight through the tube, which sometimes is fixed in a window shutter; secondly, of a condenser, or large lens, for converging the beam upon the object; and, thirdly, of a small lens, or magnifier, for throwing an enlarged image of the object at its focus upon a screen in a dark room or in a darkened box.

See also: Solar

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in classic literature ?
"Why, in truth, sir," was Monte Cristo's reply, "man is but an ugly caterpillar for him who studies him through a solar microscope; but you said, I think, that I had nothing else to do.
I'd ask Katterfelto if he really invented the solar microscope.